Summer temperatures are usually warmer than
A. winter temperatures.
B. spring temperatures.
C. autumn temperatures.
D. all of these

The de broglie relation λ=h/p can be rewritten in terms of the wave number k as p=kℏ. recall that wave number is defined by k=2π/λ. using the fact that λ=v/f, find the wave numbers k1 and k2 corresponding to frequencies f1 and f2. express your answer as two expressions

What would the difference of spectral lines emitted by hydrogen gas in distant galaxies which is normally found at a wavelength of 21 cm on earth, be observed at 21.1 centimeters?

Write the equation for momentum, first using symbols for the variables, then using words for the variables.